SPD reported is different to that on DIMM - TWIN2x2048-6400 G

[Dave_C]

Hello, had a poke around these forums and help but haven't found an answer here.

 

I recently bought 2 sets of TWIN2x2048-6400 G to use in 2 identical new systems. The timings on the physical module itself (and as purchased) are 5-5-5-12 - exact modules as shown on http://www.corsairmemory.com.au/proddetail.php?prod=TWIN2X2048-6400

 

However, in CPU-Z, the SPD reported are:

 

400Mhz, 5-5-5-18

270Mhz, 4-4-4-13

 

Why is the SPD for the 400Mhz rating different to what's physically on the DIMM (should be 5-5-5-12)?

 

The reason behind checking this is that one set of RAM causes random reboots in 2 identical machines. The RAM is defaulting to the 270Mhz speed above. MEMTEST run several times has given ONE error, but other times runs fine.

 

If I force the timings back to 5-5-5-12 as per the physical info on the DIMM, the system appears to be stable and has no reboots (although for some reason CPU-Z it says 350Mhz instead of 400Mhz, even though it's forced to 400Mhz in the BIOS)

 

Any ideas? Should the RAM be defaulting to the 4-4-4-13 speed or the 5-5-5-18 speed in the SPD setting? (Is that determined by the MB or RAM?). And of course why do I not see 5-5-5-12 in SPD as per the physical label on the module - shouldn't that be the default? Should the module work successfully at the SPD setting of 4-4-4-13 - if it is rebooting, do I suspect a faulty DIMM? (This does seem isolated to 1 out of 4 DIMMS by the way)

 

MB used in both cases is Asrock ALIVENF7G-HD720P with AMD Athlon 64 X2 4000+

 

Thanks for any help!

Dave

[RAM GUY]

5-5-5-12 are the tested settings, they are also tested at 1.9 volts. The SPD for any of our DDR800 modules is going to be programmed as 5-5-5-18, and this is what the system will boot up with unless you configure the memory manually. I would suggest that you load defaults in your BIOS and then configure the memory manually and test the modules one at a time to see if there are any failing modules. If your CPU has a multiplier that is not even (such as 11x or 10.5x) then the memory will not run at exactly 800MHz unless you either overclock or underclock the CPU.

[Dave_C]

Thanks RAM guy, appreciate your help.

 

You mention that the RAM should boot up at 5-5-5-18 - but when set to auto-detect everything, CPU-Z says the RAM is defaulting to 270Mhz 4-4-4-13 (and PC has the random reboot issues). Works perfectly at 5-5-5-12 by the way...

 

Is this coming down to how the MB selects which SPD to use? I have the latest BIOS for the MB though it still does this.

 

Can I expect it to run at 4-4-4-13, or does that require some other tweaking that perhaps the board is not doing, i.e. upping the voltage or something. I.e Are we looking at faulty ram if it DOESN'T run at the SPD listing of 4-4-4-13, or is that dependant on other components as well? (PS I am happy with 5-5-5-18 really, but would like it to do this automatically so as not to give grief years down the track when the PC is outside my control, and the BIOS gets reset to default settings and the reboots come back)

 

I will run the memtests as you suggest.

 

And indeed it's a 10.5 multiplier so that explains the MHZ!

 

Thanks again for your help!

[RAM GUY]

It sounds like that particular BIOS is selecting the backup SPD which is the 270MHz 4-4-4-13 settings. If you load setup/optimized defaults in the BIOS, save and exit the BIOS and then check the memory tab in CPU-Z, what are the timings that it is detecting and at what frequency?

[Dave_C]

Using BIOS defaults, they default to 270Mhz 4-4-4-13. So the MB determines this rather than the RAM... OK. Any reason you know of that it would pick the backup SPD by default?

 

I will pull the RAM out of this system and test it in my primary system (different MB type, etc). I did this already before (seemed to work fine) but I didn't check any CPU-Z settings, so I will confirm this as to what they default as in that system and post it back.

 

Thanks again!

[RAM GUY]

Sounds like the board is choosing the backup SPD, like you said. Have you tried loading the setup defaults with just one pair of modules in the system? Do you get the same numbers? Many times if you are using four modules in a system the board will need to run the memory at a slower spec do to limitations on the memory controller.

[Dave_C]

Actually I've only ever been using 1 or 2 modules in these tests, not 4 (I have 4 available as I bought 2 sets for 2 identical systems).

 

I tried a few more things:

 

1. Using just 1 module in the Asrock MB (just to see if there's a difference), it still detects the backup SPD (270Mhz 4-4-4-13)

2. Tried the Corsair RAM in a Gigabyte MB - it detects as 400Mhz 5-5-5-18

3. Tried my non-Corsair RAM in the Asrock MB - this RAM has 3 SPD settings - and in the Asrock it detects as the tightest timings as well. In the Gigabyte MB it detects as the loosest timings.

 

So it appears that this type of Asrock board is the cause of the ambitious timings (does the same in 2 Asrock MBs).

 

However, running a memtestx86 with the Corsair RAM against the tight timings on the Asrock is yielding no errors, however Windows is definately not stable with it's intermittent reboots. The problem DOES follow a particular set of RAM in terms of swapping it between 2 separate identical Asrock systems. So I'm not sure where that leaves me... I can leave it forced to 5-5-5-18 and stable, but feel it should work on the Auto-detect settings. I guess I still wonder why one set of Corsair RAM behaves well in the Asrock, and one doesn't (even though it has no errors on MemTest at the tight timings). I could maybe approach Asrock and ask them why the MB is choosing the tightest timings (from your posts and my tests with the Gigabyte MB, I am guessing this is unusual?) Can I assume though that the Corsair RAM should still be stable at the tight timings? That is something I'm still not sure of. Any last advice Ramguy?

 

Thanks!

[Xtreeme]

Had same thing with my Biostar Tforce 550 it set to aggresive timings. I would use everest and read ALL the timings in the spd. There are like 10 or so. Set all them in the bios that are listed. Mine was RC and WR that were wrong and cause instabilty -I mean really unstable at 400mhz. With those set it does 4-4-4-15 all day long in memtest86. My mobo only goes down to 1.95v so that maybe why it runs at the lower cas.

 

http://www.lavalys.com/products/overview.php?pid=3&ps=UE&lang=en

[RAM GUY]

DaveC,

 

If you would like to get the modules replaced, please use the On Line RMA Request Form and we will be happy to replace them. There may be an issue with the way that our modules are programmed and the way that the BIOS is detecting them with your board. If thats the case you may need to configure the memory manually to 5-5-5-12 at 1.9 volts, and the system should be stable at these settings.

[Dave_C]

Thanks Ramguy and Xtreeme for your advice and support.

 

Ramguy, as the RAM works fine at 5-5-5-12 set manually, I'll just stick with it. True that 2 separate 2Gb sets of identical corsair modules (as well as another vendor set of RAM) register at the faster timings in this board, but only one set of Corsair seems to have the reboot issue at that speed. So conceivably a replacement might allow me to run at the faster timing using the AUTO settings in the Bios, but I am ok with the forced settings as it runs fine like that. Got a lifetime warranty on the RAM so if it plays up at 5-5-5-12 then I still have that RMA option :)

 

Thanks again for all your help,

 

Cheers

Dave

[RAM GUY]

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